Spencer, E. W. (2003). Earth science: Understanding environmental systems. McGraw - Hill.
Chicago-čujuhus (17. p.)Spencer, Edgar W. Earth Science: Understanding Environmental Systems. Boston: McGraw - Hill, 2003.
MLA-čujuhus (9. p.)Spencer, Edgar W. Earth Science: Understanding Environmental Systems. McGraw - Hill, 2003.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.